Automatic charging device

ABSTRACT

446,229. Charging batteries; automatic control systems. WETZER, R., Pfronten, Bavaria, Germany. Aug. 16, 1935, No. 23077. [Class 38 (iv)] The voltage of a battery is maintained within two predetermined limits by supplying current at high or low charging rates controlled by a one contact relay which closes and opens at maximum and minimum voltage respectively, the contact pressure being increased by cutting out a series resistance after contact is made. The battery b is charged from the supply terminals k through the charging resistance r, part of which. may be short circuited by contact s actuated by resistance W1 to give the high charging rate. Contact m is then open and current flows from the battery of the relay R through moving coil B and resistance W1. When the voltage rises to the predetermined maximum, contact m closes and short circuits resistance W1, the increased current through coil B increasing the pressure of the contact. Contact S also opens and resistance r is then included in the charging circuit.

1 9, 1937'. R. WETZER I 2,096,440

AUTOMATIC CHARGING DEVICE Filed Aug. 14, 1935 AAAAAAA AA 1 pi w Rudb If. We tzer I NVE N TO E.

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Patented Oct. 19, 1937 PATENT OFFICE AUTOMATIC CHARGING DEVICE Rudolf Wetzer, Ptronten, Germany Application August 14, 1935, Serial No. 36,154 In Germany September 12, 1933 2 Claims.

The charging condition of accumulators or storage batteries can be controlled depending on the voltageas,generally known from the German patent 551,443 and the English patent 386,- 354-by keeping the voltage of the battery constant within predetermined limits. These patents show an arrangement as follows: The battery is charged with currents of two diflerent strengths, the smaller one of which may even be zero. When the batteryis charged with the higher current the voltage will increase to a certain maximum point. Thereupon a contact is made which short-circuits a series resistance thus increasing the contact pressure. This re-' sistance forms the winding of a polarized electromagnet, the armature of which releases and consequently reduces the charging current by changing the charging resistance. The voltage thereupon drops and the moment a minimum contact is reached another resistance is switched parallel to the relay thus again increasing the contact pressure. 'Il iis--.parallel resistance is also used as the second winding of the above mentioned polarized electromagnet which by moving its armature provides again the heavy charging of. the battery thereby increasing its voltage.

The present invention develops the above idea and gives a simpler solution of the problem, whereby the minimum contact becomes unnecessary and whereby an ordinary electromagnet with only one coil may be used instead of the polarized electromagnet with its two diflerent windings.

Figure 1 of 35 arrangement;

Figure 2 is a top view of the moving coil, showing the electric connections inside the relay R more clearly than in Figure 1; and

Figure 3 is a side view of the relay.

Figure 1 shows how the series resistance W1 forms the only winding of the electromagnetic relay F. This relay is controlled by contact m of the maximum contact relay R.

A and A1 (Figures 2 and 3) are the axles of the moving coil B. They are insulated from each other and connect with the beginning and the end of the windings of the moving coil B.' C is the pointer, D the front retarding spring, E the rear the drawing shows the general retarding spring. The points I and 2 are identi-' cal in Figures 1, 2, and 3. The electric connections are as follows: The current comes in at point I and goes tothe outer end of the rear retarding spring E. From the inner end of this spring it goes through B to the inner end of the iront retarding spring D. From there one way goes to the pointer C, the other through D to 2. Assuming the voltage of the battery b to be increasing by virtue of being charged from the slipply it through the charging resistance r, the moment the pointer C of the relay R reaches a certain predetermined position a. contact m is closed. This short-circuits the resistance W1 and increases the current in B thereby increasing the contact pressure and releasing the armature of the electromagnet F. This causes contact 3 to open and thus the charging current is diminished or entirely interrupted. The resistance W1 is selected so that the current in the moving coil B increases by the same amount when W1 is short-circuited as it decreases when, as a consequence of the smaller charging rate, the voltage of the battery b drops to its lowest point. At this minimum voltage the pointer C opens its contact m. The electromagnet F is energized again, its armature closes s and the higher charging rate attained by short-circuiting part of the charging resistance 1', provides an increasing battery voltage; and the whole process begins again.

The above explanation shows that the arrangement consists only 01'. one maximum relay with one contact for weak current and one ordinary electromagnet with one power current contact. It is understood that the invention is not limited to the exact embodiment disclosed in the above description and modifications may be made without departing from my invention and I, therefore, aim in the following claims to cover all such modiflcations'as fall within the true spirit and scope of my invention.

What I claim is:

1. Relay mechanism to automatically maintain the voltage of a storage battery constant within two predetermined limits, comprising a source of charging current, a charging circuit for said battery, an electromagnet with its armature forming part of said charging circuit and holding the latter closed as long as the magnet is energized, and a control circuit for said charging circuit, including a single short-circuit contact, 8. volt meter relay adapted to close said contact when the voltage across the battery exceeds the predetermined maximum voltage, and to open the contact, when the voltage drops below the predetermined minimum, and a resistance in series with said volt meter relay during the open position of said short-circuit contact, and so connected that it will be shunted out during the closed position of. said short circuit contact, said resistance forming the winding of said electromagnet and being adapted to reduce the voltage of the passing current to such an extent that the contact closing operation of the a charging resistance, an electromagnet having its armature arranged in series with said source of charging current and battery to cut out part of said charging resistance as long as the magnet is energized and a control circuit for said charging circuit including a single short-circuit contact, a volt meter relay adapted to close said charge.

contact when the voltage across the battery exceeds the predetermined maximum voltage, and to open the contact, when the voltage drops below the predetermined minimum, and a resistance in series with said voltmeter relay during the open position of said short-circuit contact, and so connected that it will be shunted out during the closed position of said short circuit contact, said resistance forming the winding of said electromagnet and being adapted to reduce the voltage of. the passing current to such an extent that the contact closing operation of the relay is checked until the battery has received its maximum RUDOLF W'ETZER. 

